JPS638310B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel evaporation prevention device used in automobiles, motorcycles, etc., and specifically relates to an adsorbent used therein.

For example, granular activated carbon has conventionally been generally used as an adsorbent for fuel evaporation prevention devices for automobiles. However, in the case of granular activated carbon, each particle is a particle, and when the particles are filled into a container, they come into partial contact with each other. However, since the automobile fuel evaporation prevention device is directly attached to the vehicle body, vibrations of the vehicle body during vehicle operation are directly transmitted to the container. As a result, the granular activated carbon inside the container rubs against each other, causing powdering, which can lead to functional deterioration, etc.
This can lead to a number of negative effects.

For the above reasons, the present inventor considered using activated carbon having an integrated monolith structure as an adsorbent.

As shown in FIG. 1, the monolithic activated carbon has a structure in which the ventilation passages communicate from the upper end surface to the lower end surface while being spaced apart from each other via partition walls. For this reason, when this is used as an adsorbent, the passageway is short, so the phenomenon of "blow-through" is likely to occur, and even though the monolithic activated carbon itself has sufficient adsorption capacity, it is easily generated from fuel tanks of vehicles, etc. There is a high risk that the fuel vapor will not be fully recovered and will be released into the atmosphere.

Furthermore, if activated carbon with a monolithic structure is used as is, fuel vapor from the fuel vapor generation source will be directly led to the engine suction section without passing through the activated carbon, temporarily reducing the value of the air-fuel ratio significantly (concentrating). , emissions, etc. are likely to occur, and a separate device or means for this short cut is required.

The present invention includes three monolithic structures, at least one of which is made of activated carbon material, and the three monolithic structures are stacked so that the path passing through each group of passages is meandering. By doing so, the retention time of the fuel vapor passing through the passage group of the monolith structure made of activated carbon material becomes longer due to the action of the meandering path formed by the three monolith structures, and the fuel vapor is sufficiently transferred to the activated carbon material in the passage part. It is an object of the present invention to provide a fuel evaporation prevention device that has excellent advantages such as vapor contact and good adsorption of fuel vapor.

Examples of the present invention will be shown below. In FIGS. 1 to 3, reference numeral 1 denotes a fuel vapor introduction pipe, which communicates with a fuel tank of an automobile. Reference numeral 2 denotes a mixture outlet pipe, which is connected to the upstream side of the throttle valve of the intake pipe of the internal combustion engine. 3a, 4a, 5a are check valves, 3
b, 4b, 5b are check valve springs, 6
a, b, c are filters made of materials such as nonwoven fabric or foamed urethane; 7a, b are packings made of oil-resistant rubber; 8
a and b are metal plates, 9a is a first monolith structure made of activated carbon (upper layer), 9b is a third monolith structure made of activated carbon (lower layer), and 10 is a second monolith structure made of activated carbon (middle layer). ), 11
A plurality of air openings 12 are formed in a ring shape at appropriate intervals in the thin wall portion of the lower plate 8b.
1 is a resin lid, and 13 is a resin container.

In this embodiment, as shown in FIGS. 3 and 4, the lattices of the first monolith structure 9a and the third monolith structure 9b are completely matched, and the passage groups formed by the lattice are completely matched. and the lattice of the second monolith structure 10 is shifted by 45 degrees in the circumferential direction from the lattice of the first and third monolith structures 9a, 9b, so that the arrangement of the passage groups of the second monolith structure 10 is The directions are the first and third monolithic structures 9a, 9
It is shifted by about 45 degrees from that in b, as shown in Fig. 5a. Note that the solid lines in FIG. This first,
Second and third monolith structures 9a, 10, 9
Both ends of the laminate A consisting of B, that is, the ends of the first and third monolith structures 9a and 9b are connected to the plate 8.
A and 8b are closed with no gaps. This laminate A is housed in a resin container 13, and this container 13 includes a fuel vapor introduction pipe 1, a mounting base 15a,
A lid 12 with parts 15b and the like is welded. There is a hole 80a in the center of the plate 8a that opens the center of the first monolithic structure 9a, and this hole forms the entrance and exit port for fuel vapor and mixture (desorption air and fuel vapor) to the stacked body A. ing. Also, plate 8
a also serves to fix the filter 6a. The other plate 8b has a filter 6c as described above.
The third monolithic structure 9b has a large number of air openings 11 at its positions, thereby opening the peripheral edge of the third monolithic structure 9b so that desorption air can enter into the stacked body A. Furthermore, plate 8b
serves to fix the filter 6c and also to support the laminate A. The packing 7a is actually a laminate A
This serves as an inlet for fuel vapor to flow into the filter 6a, and also serves to prevent fuel vapor from flowing to the filter 6a, thereby preventing short cuts. Filters 6a, c
This is to prevent foreign matter mixed in the desorption air from entering the stack A and furthermore the engine fuel chamber. The gasket 7b functions to completely prevent the desorption air from blowing through the gap formed between the outer peripheral portion of the plate 8a and the side wall of the container 13. In addition,
A spacer 12a provided on the lid 12 forms a space 14, and also works together with the container 13 to firmly fix the laminate A and other components attached thereto.

The method for manufacturing the monolithic structure is as follows.

Add 100 g of methyl cellulose to 1 kg of 200 mesh coal-based activated carbon powder, mix well, and use this as the first raw material. Water-soluble varnish containing 40% water-soluble imide resin (the remaining 60% is water) and 950 c.c. of water.
Add and mix. This is used as the first solution. The first solution is gradually added to the first raw material in a kneader and mixed well, and then thoroughly kneaded in a kneader.The kneaded material is put into an extruder equipped with a mold for molding a monolith structure, and A monolith structure is molded by extrusion from a monolith mold. Next, the obtained monolithic structure was dried at 60°C for 8 hours, and further heated at a heating rate of 12°C/Hr.
Raise the temperature to 120°C and hold at this 120°C for 5 hours to dry thoroughly. Finally, this monolith structure was heated at 270° C. for 2 hours in a nitrogen atmosphere to obtain a monolith structure that was sufficiently thermoset.

In the above configuration, the fuel vapor generated in the fuel tank etc. passes through the fuel vapor introduction pipe 1, and the check valve 4
The three first, second, and third monolithic structures 9a, 10, 9 of the laminate A are passed through the filter 6b through the filter 6b.
flows into b. As will be described later, passages are formed in the monolithic structures 9a, 10, and 9b that extend substantially concentrically, so that the fuel vapor is adsorbed and held by the activated carbon portion while flowing along the passages.

On the other hand, when the engine is being operated under certain conditions that allow the desorbed fuel vapor to enter the engine suction section as a mixture with the desorbing air, the desorbing air flows through the atmosphere opening 11. It enters the stack A through the filter 6c under the negative pressure of the engine. Then, it flows in the opposite direction to the aforementioned fuel vapor,
At this time, the fuel vapor adsorbed and held in the monolithic structures 9a, 10, and 9b is desorbed, passes through the filter 6a and the check valve 5a as an air-fuel mixture, passes through the air-fuel mixture outlet pipe 2 to the engine suction part, and enters the combustion chamber. It is led to and burnt.

Next, FIG. 4 shows the flow of fuel vapor and desorption air. A solid line α indicates the main flow of fuel vapor, and a dashed-dotted line α' indicates a slight flow. Here, the flow of α′ is the second
It can be controlled by the airflow resistance downstream of the filter 6a (outward of the laminate A) and the airflow characteristics of the filter 6a, and if the airflow resistance of the filter 6a is greater, the flow α' will not occur. If the ventilation resistance of the filter 6a is smaller, a flow of α' will occur, but the fuel vapor will flow into the space 14 and will be retained without leaking to the outside.
When the engine is running, it is burned together with the air-fuel mixture in the engine combustion chamber. The broken line β is the main flow of the desorption air, and the dashed double-dashed line β' is the slight flow. From this, the region β' (inner region of the filter 6a) has less desorption effect, but since it is the central region of the adsorbent, it only occupies a small amount compared to the total volume of the adsorbent, which will be discussed later. This area actually plays an important role in preventing short cuts.

As can be seen from FIG. 4, fuel vapor always flows through the first, second, and third monolithic active structures 9a,
10, 9b, even when the desorption air is flowing during engine operation, the first, second, and third monolithic structures 9a, 1
It mixes with the air-fuel mixture in the space 14 through the filter 6a and inside the air filter 6a. In this way, fuel vapor is short-circuited to the check valve 5a (which leads to the engine suction part).
Therefore, the so-called short cut phenomenon can be prevented.

Next, the flow of fuel vapor or desorption air in the configuration that is the gist of the present invention will be described. 5 and 6, FIG. 5a is a plan view of the laminate A, FIG. 5b is a monolith structure 9a, and FIG. 5c is a plan view of the laminate A.
5d shows the second monolithic structure 10, and FIG. 5d shows the third monolithic structure 9b. When fuel vapor flows in from the center Z, it spreads out concentrically as shown by diagonal lines in FIG.
As shown in cross section), the flow changes direction in the vertical direction. Here, the broken line in FIG. 6 shows the flow when a short circuit occurs, and as a result of experiments, it was found that although it occurs slightly, it does not have much effect on performance. Note that in the case of desorption air, it flows in the opposite direction.

As a result of the experiment, FIG. 7 shows a comparison of adsorption rates between an apparatus using the laminate A shown in FIG. 2 and a conventional apparatus using granular activated carbon.

FIG. 8 shows another embodiment of the present invention. In this embodiment, the size area of each passage in the passage group of the first monolith structure 9a and the third monolith structure 9b is four times that of the passage of the second monolith structure 10, and The pitch of the lattice forming the passage group of the body 9a is shifted by half a pitch with respect to the pitch of the lattice forming the passage group of the third monolith structure 9b, and the second monolith structure 1
When the distance between the lattices forming the two passages of 0 is defined as 1 unit, this 1 unit is defined as the first monolith structure 9a.
They are laminated to have the same pitch as the lattice that forms the group of passages. In other words, Fig. 8a,
At b, the partition walls A, B, and C are superimposed.

According to the above embodiment, the fuel vapor flows through the first, second, and third monolithic structures 9 as shown in FIG. 8c.
The fuel vapor flows into each of the passage groups a, 10, and 9b, and there is no short-circuit flow of fuel vapor.

9a, b and 10 a, b, c are the first, second, and third monolithic structures 9a, 1
0 and 9b are made into a rectangular shape, and a fuel vapor introduction pipe 1 and a mixture outlet pipe 2 are arranged on the upper corner side of the stacked body A made of these monolithic structures,
Further, a large number of air openings 11 are provided in a ring shape at appropriate intervals below the container 13, and the plate 8
The size of a is set so as to open the region of the laminate A that faces the inlet pipe 1 and the outlet pipe 2, and the other plate 8b has only one straight line. Continuous atmosphere opening 11
is provided, and a part of the third monolithic structure 9b is open.

The sizes of the passages of the first, second, and third monolithic structures 9a, 10, and 9b and the laminated state of these structures in this example are as shown in FIGS. 10a, b, c, and d. In other words, the partition walls A, B, and C in FIGS. 10a and 10b are superimposed on each other.

FIG. 11 shows that the size and number of passages in the first, second, and third monolithic structures (9)a, 10, and 9b are the same, and the first, third monolithic structures, and
are stacked so that the pitches of the lattices forming the passage groups are the same, and the second monolithic structure 10
, the pitch of the grid forming the passage group is the first,
This shows still another embodiment of the present invention in which the third monolith structures 9a and 9b are stacked so as to be shifted by half a pitch.

According to this embodiment, the fuel vapor flows in the direction of the arrows and flows into the passages of the second monolithic structure 10 one by one. Note that the first and third monolith structures 9
A, 9b will flow to every other passage.

The present invention is not limited to the above embodiments, but can be modified in various ways as described below.

(1) Of the laminate A, only the second monolith structure 10 corresponding to the intermediate layer is made of activated carbon material, and the other first and third monolith structures 9a and 9b are made of non-woven material such as resin material or porcelain material. Of course, it may be made of activated carbon material.

(2) In addition to the above (1), the first monolith structure 9
Only a or the third monolith structure 9b may be made of activated carbon material, and the other monolith structures may be made of the materials described in (1) above. In this case, it is preferable to increase the height dimension (in the direction in which the passage group extends) of the first and third monolithic structures 9a and 9b located at both ends of the laminate A.
Further, the intermediate second monolith structure 10 may have a reduced height dimension.

(3) First, second, and third monolith structures 9
The number of passages a, 10, 9b and the cross-sectional shape of the passages (triangular, round, etc.) may be arbitrary, and the first, second and third monolithic structures 9a, 1
0 and 9b may be in any laminated manner as long as a path passing through these passages in a meandering manner is formed.

As detailed above, the present invention includes three monolithic structures, at least one of which is made of activated carbon material, and the three monolithic structures are connected via respective passage groups. The laminated body is laminated so that the path is meandering, a plate is attached to both ends of the laminated body to close the both ends, and a hole is provided on the side of this plate or in the plate itself to open a part of both ends of the laminated body, Since one of these openings is a fuel vapor inlet and the other is a desorbed air inlet, the fuel vapor accumulates through this path due to the meandering path formed by the passage group of the three monolithic structures. Due to the increased time, the fuel vapor passing through the passages of one monolithic structure of activated carbon material is fully adsorbed by the activated carbon material of that passage group, thus significantly increasing the adsorption of fuel vapor.

Furthermore, since the desorbed air also flows through the meandering path, the adsorbed fuel vapor can be reliably desorbed and the adsorption capacity can be restored.

Furthermore, since the fuel vapor can be reliably introduced into the passages of the monolith structure made of activated carbon material as described above, it is possible to prevent the fuel vapor from entering this passage group and to shortcut it to another outlet for discharging the desorbed air. No problems arise.

Furthermore, unlike granular activated carbon, problems such as wear caused by vibration hardly occur.

As described above, the present invention can provide a fuel evaporation prevention device that is extremely excellent in fuel vapor adsorption performance, desorption performance, and vibration resistance.

[Brief explanation of the drawing]

FIG. 1 is a partially cross-sectional perspective view showing a monolith structure made of activated carbon material used for explaining the present invention, and FIG.
The figure is a partial cross-sectional view showing one embodiment of the present invention, FIG. 3 is a partial cross-sectional perspective view showing the stack of FIG. 2, and FIG. 4 is a flow diagram of fuel vapor and desorbed air in FIG. Partial cross-sectional views, FIGS. 5a to 5d are plan views of the laminate of FIG. 3 and first, second, and third monolithic structures constituting it, and FIG. 5a is a plan view of the laminate. , FIG. 5b is a plan view showing the first monolith structure and its fuel vapor adsorption range;
Figure c is a plan view showing the second monolith structure and its fuel vapor adsorption range; Figure 5 d is a plan view showing the third monolith structure and its fuel vapor adsorption range;
FIG. 6 is a cross-sectional view showing in detail the flow of fuel vapor to each monolith structure shown in FIGS. 5 a to d, FIG. 7 is a characteristic diagram for explaining the effects of the present invention, and FIGS.
c shows another embodiment of the present invention, and Fig. 8a shows another embodiment of the present invention.
is a schematic plan view showing the first and third monolith structures, FIG. 8b is a schematic plan view showing the second monolith structure, and FIG. 8c is a schematic plan view showing the first, second, and third monolith structures. 9a and 9b show another embodiment of the present invention, and FIG. 9a is a front sectional view,
Figure 9b is a sectional view taken along line AA in Figure 9a, Figure 10a
- d show the laminate and the first, second, and third monolith structures used in the example of FIGS. 9a and b, and FIG. 10 a is a schematic plan view showing the second monolith structure. Figure 10b is a schematic plan view showing the first and third monolithic structures, and Figure 10c is a laminate in which the first, second, and third monolithic structures are stacked and the fuel vapor flow thereof. A sectional view showing,
FIG. 10d is a view taken along arrow D in FIG. 10c, and FIG. 11 is a sectional view showing a stacked body and its fuel vapor flow in still another embodiment of the present invention. 8a, 8b... Plate, 9a... First monolith structure, 9b... Third monolith structure, 10... Second monolith structure, 11... Atmospheric opening, 80a... Hole.

Claims (1)

[Claims] 1. In a fuel evaporation prevention device adapted to adsorb fuel vapor from a fuel vapor generation source, three first, second, and third monolith structures each having a large number of passages separated by partition walls are provided. wherein at least one monolithic structure is constructed of an activated carbon material, and the first, second, and third monolithic structures define three groups of passageways through the first, second, and third monolithic structures. The first, second, and third monolith structures are stacked so that the path passing through the stack is meandering, and plates are attached to both ends of the stack to close the ends, and the shape of the plates is set. Alternatively, a hole is provided in this plate to partially open both ends of the laminate;
A fuel evaporation prevention device characterized in that one of the opening portions is a fuel vapor introduction portion and the other is a separated air introduction portion, and both of the opening portions are arranged at positions not facing each other. 2 the first and third portions located at both ends of the laminate;
The pitches of the lattice forming the passage group of the monolith structure are the same, and the lattice forming the passage group of the second monolith structure located in the middle of the stack is the same as that of the first and third monolith structures. 2. The fuel evaporation prevention device according to claim 1, wherein the fuel evaporation prevention device is disposed at an angle of 45° from that of the body. 3. Individual passages of the passage groups of the first and third monolith structures located at both ends of the laminate are different from individual passages of the passage group of the second monolith structure located in the middle of the laminate. the area of the lattice forming the passage groups of the first and third monolithic structures is shifted by half a pitch from each other; When the distance between the lattices forming the two passages in is 1 unit, this 1 unit is the same as the pitch of the lattice forming the passage group of the first monolith structure or the third monolith structure. A fuel evaporation prevention device according to claim 1, characterized in that: 4. The fuel evaporation prevention device according to any one of claims 1 to 3, wherein the second monolith structure located in the middle of the stacked body is made of the activated carbon material. 5. The structure according to claim 4, wherein a height dimension of the second monolith structure along the direction in which the passage group extends is larger than a height dimension of the first and third monolith structures. Fuel evaporation prevention device. 6. The method according to claim 4 or 5, wherein the first and third monolithic structures are made of a non-activated carbon material such as resin or porcelain that is resistant to fuel deterioration. Fuel evaporation prevention device. 7. The fuel evaporation prevention device according to claim 4 or 5, wherein the first and third monolithic structures are also made of activated carbon material.